This invention relates to optical repeaters for telecommunication transmission systems, particularly for undersea systems and particularly but not exclusively to glanding arrangements for such repeaters.
In an optical undersea telecommunications system the major problems are the maintenance of a vapour and water free environment and an assembly of the electrical and optical components which facilitates manufacture and testing prior to installation.
U.K. Patent application No. 2091901A provides a sealed chamber on the front of the bulkhead and two cable glands, one through the chamber wall and one through the bulkhead, to provide a sealed environment within the repeaters and enable fibre splicing in the chamber. However this arrangement is not ideal; in particular it is difficult to see how either gland can be factory tested, other than with gas under pressure, without damaging the cable or the gland.
U.S. Pat. No. 4,345,816 shows an optical fibre introducing equipment for an optical submerged repeater and teaches the use of a small diameter metal cylinder with an insertion hole for receiving an optical fibre more than several times the diameter of the coated optical fibre, and gluing the fibre into the insertion hole with part of the coating removed. The disadvantage of this arrangement is the use of adhesive such as epoxy for withstanding the ultimate pressure differential which may occur in use of the repeater and the fact that no epoxy adhesive has yet been found, to our knowledge, which provides hermeticity to the degree required for a submerged repeater.